Fuel injection type spark plug with an atomizing nozzle



W. WEINS April 25, 1967 FUEL INJECTION TYPE SPARK PLUG WITH AN ATOMIZINGNOZZLE Filed April 27, 1965 2 Sheets-Sheet 1 W. WEINS April 25, 1967 FUEL INJECTION TYPE SPARK PLUG WITH AN A'TOMIZING NOZZLE 2 Sheets-Sheet 2 Filed April 2'?, 1965 l .Y ff, /IA- nu 1. 7 ...v l

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United States Patent @ffice '3,3 l6,437 Patented Apr. 25, 1967 FUEL INJECTEN TYPE SPARK PLUG WllTH AN ATOMIZENG NOZZLE Walter Weins, Stuttgart, Germany, assigner to Robert Bosch GmbH-l, tuttgart, Germany Filed Apr. 27, 1965, Ser. No. 451,199 Claims priority, application Germany, .lune 11, 1964, is 77,192 6 Claims. (Cl. 313-120) The present invention relates to spark plugs, especially for use in gas turbines but also in other types of internal combustion engines. More particularly, the invention relates to a spark plug which is combined with a fuel injection nozzle and wherein atomized fuel issuing from the iniection n-ozzle flows along the spark gap between the inner and outer electrodes of the spark plug.

A serious drawback of presently utilized spark plugs which are combined with fuel injection nozzles is that such spark plugs must be provided with expensive, complicated and short-lived sealing elements serving to prevent uncontrolled flow of fuel between the component parts of the spark plug. Also, many difficulties arise in properly mounting the center electrode so that this electrode can withstand substantial pressures and is not affected by expansion or contraction which takes place in response to temperature changes. In fact, proper mounting of the center electrode often presents serious problems in a conventional spark plug without an injection nozzle, and such problems are aggravated in spark plugs of the type to which my present invention pertains because the fuel must be guided through the center electrode. Particularly serious problems arise in guiding the fuel through that part of the center electrode which is surrounded by the insulator of the spark plug. To my knowledge, all presently used spark plugs with fuel injection nozzles are very complicated, very expensive and their usefullife is substantially shorter than the luseful life of conventional spark plugs.

Accordingly, it is an important object of the present invention to provide a comparatively simple and inexpensive spark plug whose center electrode is arranged to convey fuel to the injection nozzle in a novel way, without permitting leakage of fuel, and which is constructed and assembled with a view to stand long periods of actual use.

Another object of the invention is to provide a novel fuel-conveying structure for use in a spark plug of the just outlined characteristics.

A further object of the invention is to provide a fuel injection nozzle which may be utilized in such spark plugs.

An additional object of the invention is to provide a fuel injection nozzle which can be installed and utilized in various types of spark plugs.

Still another object of the invention is to lprovide a novel sealing structure for use in a spark plug wherein the center electrode conveys fuel to an injection nozzle.

Briefly stated, one feature of my invention resides in the provision of a spark plug, particularly for use in gas turbines, which kcomprises a center electrode including a tubular front portion, a median portion consisting of current-conducting non-metallic (preferably vitreous) material, and a rear portion, an axial blind bore provided in the median portion and communicating with the interior of the front portion, a substantially radial blind bore provided in the median portion and communicating with the axial bore, a tubular insulator sealingly surrounding at least the median portion of the center electrode and having a substantially radial bore communicating with the first mentioned radial bore, a metallic shell surrounding the insulator and defining therewith an annular compartment which communicates with the radial bore of the insulator, means for sealing the axial ends of the compartment, a nipple or other suitable fuel-admitting means connected with the shell and arranged to discharge into the compartment so that fuel entering through the fuel admitting means fiows through the bores and into the interior of the front portion, an outer electrode secured to the shell and spac-edly surrounding the front portion of the inner electrode, and a metallic fuel injection nozzle connected to the front end of the front portion and having duct means communicating with the interior of the front portion.

The nozzle preferably constitutes a prefabricated element of the spark plug and may resemble atomizing nozzles of the type used in oil burners. For example, the nozzle may define an internal atomizing chamber which receives fuel through one or more tangential inlet ducts and discharges atomiz-ed fuel into a funnel-shaped tip having an annular front end face which may define with the outer electrode a spark gap. Alternatively, the nozzle may be welded toa rod-shaped extension which terminates in close proximity to an inwardly extending lug provided at the front end of the annular outer electrode.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved spark plug itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific .embodiments with reference to the accompanying drawings, in which:

FIG. 1 is an axial section through a spark plug which embodies one form of my invention;

FIG. 2 is an enlarged axial section through a fuel injection nozzle which forms part of the spark plug shown in FIG. l;

FIG. 3 is a transverse section as seen in the direction of arrows from the line III-III of FIG. 2; and

FlG. 4 is an axial section through a modified spark plug.

Referring first to FIG. 1, there is shown a spark plug 1 which comprises a metallic fuel injection nozzle 2. The nozzle 2 receives fuel from a supply conduit which discharges into the central opening 3 of a fuel admitting member here shown as an externally threaded nipple 4. This nipple is sealingly received in a suitable aperture of the metallic shell 5 and extends radially outwardly substantially midway between theaxial ends of the shell. An elongated tubular insulator 6 is coaxially received in and extends beyond the rear end of the shell 5. The insulator 6 and the shell 5 define between themselves an annular compartment 9 whose rear and front axial ends are respectively sealed by annular gaskets 7 and 8. The compartment 9 communicates with and receives fuel from the discharge end of the opening 3 in nipple 4. This compartment surrounds the peripheral surface 10 of the insulator and discharges into a rearwardly inclined radially or substantially radially extending bore 11 provided in the insulator and communicating with a similarly inciined radial bore 11a formed in a sealing plug 14 which consists of current-conducting vitreous material. The plug 14 contains in known manner 78% glass and 22% finely divided copper particles, thereby forming an electrically connecting portion of the center electrode and the plug 14 completely iil-ls the central portion of the insulator 6 and is further provided with an axially and forwardly extending blind bore 15 which communicates with the rear end of the radial bore 11a. The forward end of the bore 15 communicates with -a central bore 12a provided in the prefabricated cylindrical front portion 12 of a center electrode, the front end or foremost end of the front portion 12 being threadedly connected with the in- 3 jection nozzle2. Thus the stream of fuel entering through the opening 3 of thevnipple 4 flows through the compartment 9, thereupon through the coaxial radially extending bores 11, 11a, through the axial bore 15 and finally through the axial bore 12a, i.e., through the interior of the front Y portion 12.` The center electrode includes the aforementioned front portion 12, the plug 14 Which constitutes the central or median portion thereof, and a rear portion 13 which is embedded in the rear end of the plug 14 and is connected with a lead, not shown. In the illustrated embodiment, the front and rear portions 12, 13 of the center electrode are threadedly secured to the respective ends of the -plug 14. The diameter of the axial bore 15 is identical with the diameter of the axial V'bore 12a, yand the common axisrof these bores coincides with the axis'of the center electrode. y

vThe bores 11, 11a, 15 and 12a together define a continuous path of constant cross-sectional area through which the fuel can Vow from the annular compartment 9 to the injection nozzle 2. This isnthe sole path in which the fuel can ow to the nozzle. The rear end portion of the shell 5 is formed with internal threads to take the forward end of a protective tube 16. The rear end of the tube :16 isalso formed with external threads, as at 17', and is connected With a suitable conductor cable, not shown. The front end portion of the shell 5` receives the rear end ofJa hollow cylindrical cap 18 which constitutes the outer electrode'. The nfront end of the outer electrode 18 is formed with an inwardly extending annular lfiange 19a which defines a circular aperture 19.

The insulator 6 is formed with a circumferential shoulder which serves as a stop for the rear gasket 7. A-third annulargasket 21 is compressed by the front end face of the tube 16,- and the space between the gaskets 7, 21 is f Vfilledrwith a mass of pulverulent sealing material.V This mass 20 is automatically compressed between the gaskets 7,21 when the tubek 16 is screwed home.

TheV construction of the injection nozzle 2 is illustrated in FIGS. 2 and V3. The Central section of this nozzle definesV an internal atomizing chamber 22 whose rear end is sealed bya sealing lmember or stopper 29 provided in the rear section of the nozzle. VThe annular Wall surrounding the chamber 22 is formed with two tangentially extending inlet ducts 23 (see particularly FIG. 3) which are located substantially diametricaliy opposite each other. The streams of fuel entering thek chamber 22 through the ducts 23 are atomized and such atomized fuelv then flows along the conical surface ofv a front Wall 24 into a centrally located discharge duct 25 which terminates in the bottomzone of a funnel-shaped front section` or vtip 26 ofthe nozzle 2. This front section is formed With a pair of axially extending air admitting slots 27 (only one'shown in FIG. 2) and its front end face 28 defines with thefiange 19a of the'cap 18 an annular spark gap across which the high-voltage surges must jump in order, `to ignite atomizedv fuel issuing from the tip 26. Thus, it

will be seenV that the nozzle 2 actually constitutes the foremost part of the center electrode. The internal surface Iof the lwall'24 diverges rearwardly toward thev ducts 23.

Y, The; stopper 29 prevents uncontrolled entry of rfuel into the atomizing chamber 22, ie., this chamber can receive fuelA only through the ducts 23, and such ducts receive fuel through axially parallel channels 23a provided in the jperiphery of a rear Vsection of the nozzle 2 which surrounds the stopper 29. The central section of the nozzle '2 which surrounds the atomizing chamber 22 'is formed with external threads 30 and meshes with internal threads Y p 12 with a force which suffices to insure that the shoulder `31-omesginto sealing abutmentwith the front end face l n of the .fr-ont portion 12 .so that there is no need for addi- 4 tional sealing means. Also, when the shoulder 31 abuts against the front portion 12, the nozzle 2 is automatically held against uncontrolled rotation with reference to the center electrode.

FIG. 4 illustrates a somewhat modified spark plug 40 having a shell 5' which is not provided with external the shell 5 Vand is secured thereto by spot welding as indicated at 52. This outer electrode has six uniformly distributed circular inlets 43 which admit air to the funnel-shaped tip of the injectionV nozzle 2. The injection nozzle is welded at 2" to the rear end of a rod-shaped extension 41 which constitutes the foremost element of the center electrode and defines a spark gap with one of several inwardly extending lugs 42 provided at the front end of the outer electrode 1S. The lugs 42 are obtained by slitting the electrode 181and by bending the. portions between adjoining slits inwardly toward the axis of the spark plug 40. n Y

The structure of FIG. 4 further comprises a filtering unit which is installed in the fuel admitting nipple 4. The filtering unit comprises a sleeve 44 which is Vscrewed into the intake end 45 of the nipple 4'and whose left-hand end accommodates a tubular head 46 forming part of a cylindrical carrier 47 for an elongated cylindrical sieve 48. The front end of the sieve 48 is sealed by a U-shaped clamp 49 so that fuel entering through the parts 46, 47

flows through the interstices of the sieve 48 to penetrate v veal the gist of the present invention that others can, by.

applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specic aspects of my contribution to the art and, therefore, such adaptations should and are intended to be comprehended within the meaning and rangey of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. A spark plug, particularly for use in gas turbines, comprising la center electrode including a tubular front portion having a front end, a median portion consisting of current-conducting non-metallic material, and a rear portion, said median portion having an axial blind bore communicating with the interior of said front portion and a substantiallyV radial blind bore communicating with said axial bore; a tubular insulator sealingly surrounding said median portion and having a substantially radial bore communicating with the radial bore of said median portion; a metallic shell surrounding said insulator and defining vtherewith an annular compartment which communicates Y ends of said compartment; fuel admitting means sealingly connected with said shell and arranged to discharge fuel solely into said compartment so that such fuel iioWs only through said bores and into the interior of said front portion; an outer electrode securedrto said shell and spacedly surrounding said front end and having duct means communicating with the interior of said front portion; and a fuel injection nozzle connected to said front end and having duct means communicating with the interior of said front portion.

2. In a spark plug, particularly for use in gas turbines, a center electrode including a tubular front end portion having la front end and a rear end, and a second portion consisting of current-conducting vitreous material and sealingly connected with the rear end of said front por-tion, said second portion having an axially extending blind bore discharging into the interior of said front portion and a substantially radially extending blind bore discharging into said axially extending blind bore; an insulator sealingly surrounding said second portion and having a substantially radial bore constituting an outward extension of said radially extending blind bore, said radial bore extending to the periphery of said insulator; a metallic shell surrounding said insulator and defining therewith a fuel accommodating compartment communicating with said radial bore; sealing means provided between said insulator and said sleeve at both axial ends of said compartment; fuel admitting means discharging into said compartment so Ithat fuel admitted by said last named means can flow solely through said bores and into the interior of said front portion; and an atomizing nozzle secured to said front end and having duct means communicating with the interior of said front portion.

3. A spark plug, particularly for use in gas turbines, comprising a center electrode including a tubular front portion having a front end, a median portion consisting of current-conducting vitreous material, and a rear portion, said median portion having an axial blind bore communicating with the interior of said front portion and a substantially radial blind bore communicating with said axial bore; a tubular insulator sealingly surrounding said median portion .and having a substantially radial bore communicating with the radial bore of said median portion; a metallic shell surrounding said insulator and dening therewith an annular compartment which communicates with the bore of said insulator; means for sealing the axial ends of said compartment; fuel admitting means connected with said shell and arranged to discharge fuel into said compartment so that such fuel ows through said bores and into the interior of said front portion; an outer electrode secured to said shell and spacedly surrounding said front portion; and a fuel injection nozzle including a rear section defining with said front end at least one fuel conveying channel, and a funnel shaped front section having an annular front edge portion closely adjacent to and defining a spark gap with said outer electrode, said nozzle further having an internal atomizing chamber, at least one substantially tangentially extending inlet duct for admitting fuel from said channel into said chamber, and a centrally located discharge duct connecting said chamber with the interior of said funnel.

4. In a spark plug, particularly for use in gas turbines, a center electrode including a tubular front end portion having a front end yand a rear end, and a second portion consisting of current-conducting vitreous material and sealingly connected with the rear end of said front portion, said .second portion having an axially extending blind bore discharging into the interior of said front portion and a substantially radially extending blind bore discharging into said axially extending blind bore; an insulator sealingly surrounding said second portion and having a substantially radial bore constituting an outward extension of said radially extending blind bore, said lradial bore extending to the periphery of said insulator; a metallic shell surrounding said insulator and ldefining therewith a fuel accommodating compartment communicating With said radial bore; sealing means provided between said insulator and said sleeve at both axial ends of said compartment; fuel admitting means having an opening discharging into said compartment so that fuel admitted through said opening into said compartment can ow solely through said bores and into the interior of said front portion; filter means provided in said fuel admitting means; and an atomizing nozzle secured to said front end and having duct means communicating with the interior of said front portion.

'5. A spark plug, particularly for use in gas turbines, comprising a center electrode including a tubular front por-tion having a front end, a median portion consisting of current-conducting non-metallic material, and a rear portion, said median `portion having an axial blind bore communicating with the interior of said front portion and a substantially radial blind bore communicating with said axial bore; a tubular insulator sealingly surrounding said median portion land having a substantially radial bore communicating with the radial bore of said median portion; a metallic shell surrounding said insulator and delining therewith an lannular compartment which communi cates with the bore of said insulator; means for sealing the axial ends of said compartment; fuel admitting means connected with said shell and arranged to discharge fuel into said compartment so that such fuel -ows through said bores and into the interior of said front portion; an outer electrode secured to said shell and spacedly surrounding the said front portion; .and a fuel injection nozzle including a rear section defining with said front end at least one fuel conveying channel, and a funnel shaped front section discharging into said outer electrode, said nozzle further having an internal atomizing chamber, at least one tangentially extending inlet duct connecting said channel with said chamber, an axially extending discharge duct connecting said chamber with the interior of said front section, and a rod-shaped extension projecting forwardly from said front section, said outer electrode having a front end portion defining a spark gap with the foremost end of said extension.

6. VIn a spark plug, particularly for use in gas turbines, a center electrode including a tubular front end portion having a front end and a rear end, land a second portion consisting of current-conducting vitreous material and sealingly connected with the rear end of said front portion, said second portion having 'an axially extending blind bore discharging into the interior of said front portion and a substantially radially extending blind bore discharging into said axially extending blind bore; an insulator sealingly surrounding said second portion and having a substantially radial bore constituting an outward extension of said radially extending blind bore, said radial bore extending to the periphery of said insulator and the latter further comprising a tubular portion extending rearward- -ly and beyond said median portion; a shell sealingly surrounding said insulator; a metallic protective tube secured to said shell and surrounding said tubular portion of said insulator; fuel admitting means connected with said shell and having an opening arranged to admit fuel solely to the bore of said insulator so that the thus admitted fuel is compelled to ilow into the interior of said front portion; and an atomizing nozzle secured to said front end and having duct means communicating with the interior of said front portion.

References Cited by the Examiner UNITED STATES PATENTS 2,292,409 8/1942 Steward 313--120 X 2,459,286 1/1946 Rabezzana et al. 313-120 X 3,204,139 8/1965 Candelise 313712() JAMES W. LAWRENCE, Primary Examiner,

C, R. CAMPBELL, Assistant Examiner` 

1. A SPARK PLUG, PARTICULARLY FOR USE IN GAS TURBINES, COMPRISING A CENTER ELECTRODE INCLUDING A TUBULAR FRONT PORTION HAVING A FRONT END, A MEDIAN PORTION CONSISTING OF CURRENT-CONDUCTING NON-METALLIC MATERIAL, AND A REAR PORTION, SAID MEDIAN PORTION HAVING AN AXIAL BLIND BORE COMMUNICATING WITH THE INTERIOR OF SAID FRONT PORTION AND A SUBSTANTIALLY RADIAL BLIND BORE COMMUNICATING WITH SAID AXIAL BORE; A TUBULLAR INSULATOR SEALINGLY SURROUNDING SAID MEDIAN PORTION AND HAVING A SUBSTANTIALLY RADIAL BORE COMMUNICATING WITH THE RADIAL BORE OF SAID MEDIAN PORTION; A METALLIC SHELL SURROUNDING SAID INSULATOR AND DEFINING THEREWITH AN ANNULAR COMPARTMENT WHICH COMMUNICATES WITH THE BORE OF SAID INSULATOR; MEANS FOR SEALING THE AXIAL ENDS OF SAID COMPARTMENT; FUEL ADMITTING MEANS SEALINGLY CONNECTED WITH SAID SHELL AND ARRANGED TO DISCHARGE FUEL SOLELY INTO SAID COMPARTMENT SO THAT SUCH FUEL FLOWS ONLY THROUGH SAID BORES AND INTO THE INTERIOR OF SAID FRONT PORTION; AN OUTER ELECTRODE SECURED TO SAID SHELL AND SPACEDLY SURROUNDING SAID FRON END AND HAVING DUCT MEANS COMMUNICATING WITH THE INTERIOR OF SAID FRONT PORTION; AND A FUEL INJECTION NOZZLE CONNECTED TO SAID FRONT END AND HAVING DUCT MEANS COMMUNICATING WITH THE INTERIOR OF SAID FRONT PORTION. 